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Discussion Starter #1
Has anyone ever tried running twin
turbos on an l28 engine. A T-3 is
capable of producing ~300 hp. So,
instead of using a large T-O4 turbo with lots of lag to produce ~500 hp,
could you instead use twin T-3's. Would that reduce lag?

Thanks
 

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Discussion Starter #2
Yeah two smaller turbos would spoolup quicker, but the problem comes in with space. Since we've got an in-line, you would have to have both turbos next to each other with a manufactured exhaust manifold feeding into a twin manifold set-up all on the same side. I think it would too tough, although I have heard of a twin turbo CARB set-up. But I bet that is a pain and a bitch to set-up. It seems like if you want ~500hp, then you should go with a T-04 turbo and a 75-100 shot of NOS for low-end power before the turbo kicks in.

just thinkin'.

Later,
LuZifer
'83 turbo project

> Has anyone ever tried running twin
> turbos on an l28 engine. A T-3 is
> capable of producing ~300 hp. So,
> instead of using a large T-O4 turbo with
> lots of lag to produce ~500 hp,
> could you instead use twin T-3's. Would that
> reduce lag?

> Thanks
 

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I am not so sure about reduced lag on a twin turbo setup, especially if you use 2 t3 units. OK, on a single turbo setup you have 2.8L of discplacement providing exhaust to spool the single turbo. Now on a twin turbo setup, you have 1.4L of discplacement providing exhaust to spool each of the t3 units. You will have to generate higher RPMs to provide enough exhaust to spool the turbo because of the decreased discplacent per turbo. Perhaps a smaller turbo would provide you with increased spoolup time, but probably not 2 t3 units. Anyway, I have been looking into doing the twin t3 setup on my car. There is plenty of room to do it and besides it would be pretty cool to say you had a twin turbo 240z.
 

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Discussion Starter #4
Super Turbo?

Dudes!
How about turbo and blower together. That had been done before. Not on Z, but done.
Imagine that?

PS
240Z Turbo - let us think together. I was toying with eather one of my ideas for a while now.
 

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Discussion Starter #5
> I am not so sure about reduced lag on a twin
> turbo setup, especially if you use 2 t3
> units. OK, on a single turbo setup you have
> 2.8L of discplacement providing exhaust to
> spool the single turbo. Now on a twin turbo
> setup, you have 1.4L of discplacement
> providing exhaust to spool each of the t3
> units. You will have to generate higher RPMs
> to provide enough exhaust to spool the turbo
> because of the decreased discplacent per
> turbo. Perhaps a smaller turbo would provide
> you with increased spoolup time, but
> probably not 2 t3 units. Anyway, I have been
> looking into doing the twin t3 setup on my
> car. There is plenty of room to do it and
> besides it would be pretty cool to say you
> had a twin turbo 240z.

Oh, I agree it would be cool to say that, but I would think that a hybrid t3/t4 turbo would do a great job and there would be plenty of room for the tubing for an intercooler. Is there enough room for four sets of tubing and two intercoolers up front for a twin turbo set-up? I don't exactly know, but I would think it would be hard to do. Then you got to come back for the intake. How do you do that? I'm not knockin' what your saying or thinking, I thought of something like that too, I just didn't ever think of how to do it and to do it right so its reliable and powerful. That's why I'm going with a single turbo configuration.

What about the supercharger/turbocharger setup mentioned? How do go from one induced air to the other?

Brainstorming is the forefront of innovative thinking.

Keep it up,
LuZifer
'83 turbo project
 

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Discussion Starter #6
> Oh, I agree it would be cool to say that,
> but I would think that a hybrid t3/t4 turbo
> would do a great job and there would be
> plenty of room for the tubing for an
> intercooler. Is there enough room for four
> sets of tubing and two intercoolers up front
> for a twin turbo set-up? I don't exactly
> know, but I would think it would be hard to
> do. Then you got to come back for the
> intake. How do you do that? I'm not knockin'
> what your saying or thinking, I thought of
> something like that too, I just didn't ever
> think of how to do it and to do it right so
> its reliable and powerful. That's why I'm
> going with a single turbo configuration.

> What about the supercharger/turbocharger
> setup mentioned? How do go from one induced
> air to the other?

> Brainstorming is the forefront of innovative
> thinking.

> Keep it up,
> LuZifer
> '83 turbo project

You would need a dual inlet at the intake manifold. You shouldn't need
intercooling for the super, and you would for the turbo. As far as how to
switch from one to the other, I read
that the last gen RX-7's used a plumbing loop on the larger turbo to
keep it from coming on to soon. So the
super would power up to 8psi and
ideally the turbo would take over from
that point on. To keep the turbo from
adding boost to the engine before the
super reaches 8 psi, you can: 1. Use
a butterfly valve on the pipe that
leads from the intake manifold to the
turbo. You'll want it to remain closed
until the super reaches 8 psi then it
will open and let the turbo do its
business. Of course, while that
butterfly valve is closed the air is
going to back up into the compressor
side of the turbo. This is not going
to make your turbo very happy. To
relieve this pressure, you will need
to make a dump tube that leads back to the inlet of the turbo. This dump tube
will also be controlled by a butterfly
valve. It will remain open until the super reaches 8 psi allowing the turbo
to vent off the pressure back into its own inlet, then it will close when
the super reaches 8 psi so that all
the boost is now routed to the intake.
It would be easier to control the
valves electronically since they work
in exact opposites. When one valve is
open the other will be closed. So you can wire them out of phase. Let me make it clear that when I say inlet
I'm referring to the hole in the
center of the turbo, and when I say
intake I'm referring to the intake
manifold. Also, I use 8 psi for the
super because anything higher would
require an intercooler. You don't
want to mess with dual intercoolers.
All the check valves are on the turbo
side of the system, and should not
interfere with the super in any way.
And the dump tube should be as close
to the turbo as possible. Hope this
makes sense. If you're unclear about
anything ask me.

Carlos L.
 

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Discussion Starter #7
Diminishing returns

Albeit, the turbo would kick in to take over the boosting, you reach a point of diminishing returns, because your still dragging the belt on the supercharger - that is a BIG horsepower robber if it is not in use. Secondly, if it is a geared, impeller driven unit, you have to keep it lubricated too, and you also run the risk of over-spinning the turbine and breaking something, because most supers are geared for v8's that rarely see above 6500rpm. You and I both know that the L series motor is capable of way above that, and if you are dragging the impeller along at say 50,000rpm, something could well break. The purpose of the turbo is to let the exhaust gases spin it up, the super spins it up at engine rpm's. The best bet would be to get a super unit geared for higher rpm's (geared down, I guess) intercool it, and run the bejeezus out of the boost. They make units upwards of 21lbs nowdays, plus the intake charge would be FAR cooler with an intercooled super than it would by an intercooled turbo - by default it would be anywhere from 70 to 110 degrees difference in ambient temperature, and that spells HP!! Timing can be advanced much farther without the risk of detonation, and, depending on carbureted or injected, a modified fuel curve could also benefit the motor by adjusting to the amount of boost being produced at a given rpm range. I have been mulling over the idea for a while, I have a blown/intercooled Mustang and it is a very efficient way to get HP without having to buy ANYTHING else for the car such as a timing management system etc.. Just another idea to throw into the fire!

Tim

> You would need a dual inlet at the intake
> manifold. You shouldn't need
> intercooling for the super, and you would
> for the turbo. As far as how to
> switch from one to the other, I read
> that the last gen RX-7's used a plumbing
> loop on the larger turbo to
> keep it from coming on to soon. So the
> super would power up to 8psi and
> ideally the turbo would take over from
> that point on. To keep the turbo from
> adding boost to the engine before the
> super reaches 8 psi, you can: 1. Use
> a butterfly valve on the pipe that
> leads from the intake manifold to the
> turbo. You'll want it to remain closed
> until the super reaches 8 psi then it
> will open and let the turbo do its
> business. Of course, while that
> butterfly valve is closed the air is
> going to back up into the compressor
> side of the turbo. This is not going
> to make your turbo very happy. To
> relieve this pressure, you will need
> to make a dump tube that leads back to the
> inlet of the turbo. This dump tube
> will also be controlled by a butterfly
> valve. It will remain open until the super
> reaches 8 psi allowing the turbo
> to vent off the pressure back into its own
> inlet, then it will close when
> the super reaches 8 psi so that all
> the boost is now routed to the intake.
> It would be easier to control the
> valves electronically since they work
> in exact opposites. When one valve is
> open the other will be closed. So you can
> wire them out of phase. Let me make it clear
> that when I say inlet
> I'm referring to the hole in the
> center of the turbo, and when I say
> intake I'm referring to the intake
> manifold. Also, I use 8 psi for the
> super because anything higher would
> require an intercooler. You don't
> want to mess with dual intercoolers.
> All the check valves are on the turbo
> side of the system, and should not
> interfere with the super in any way.
> And the dump tube should be as close
> to the turbo as possible. Hope this
> makes sense. If you're unclear about
> anything ask me.

> Carlos L.
 

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> Has anyone ever tried running twin
> turbos on an l28 engine. A T-3 is
> capable of producing ~300 hp. So,
> instead of using a large T-O4 turbo with
> lots of lag to produce ~500 hp,
> could you instead use twin T-3's. Would that
> reduce lag?

> Thanks
Look at the twin turbo Skyline in Japan. 2.6liters of inline 6 terror.
 

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Re: Diminishing returns

>The best bet would be to get a
> super unit geared for higher rpm's (geared
> down, I guess) intercool it, and run the
> bejeezus out of the boost. They make units
> upwards of 21lbs nowdays, plus the intake
> charge would be FAR cooler with an
> intercooled super than it would by an
> intercooled turbo - by default it would be
> anywhere from 70 to 110 degrees difference
> in ambient temperature, and that spells HP!!

Okay, you lost me here. Why exactly would you expect the intake air charge to be 70-110 degrees cooler with the supercharger? The centrifugal type blowers are essentially a gear driven turbo impeller, so I wouldn't expect them to be inherently more efficient on the compressor side. As far as cold air intake, you will still have the same intercooler tube routing problems that you would have with the turbo.

Okay, perhaps you could mount the supercharger on the opposite side of the engine from the intake manifold. This would probably give you cooler inlet air temps, and possible access around the radiator. But with an intercooler up front, there insn't much room left up there for an air cleaner.
Was this the sort of thing you had in mind?
 

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Discussion Starter #10
Re: Diminishing returns

> Albeit, the turbo would kick in to take over
> the boosting, you reach a point of
> diminishing returns, because your still
> dragging the belt on the supercharger - that
> is a BIG horsepower robber if it is not in
> use. Secondly, if it is a geared, impeller
> driven unit, you have to keep it lubricated
> too, and you also run the risk of
> over-spinning the turbine and breaking
> something, because most supers are geared
> for v8's that rarely see above 6500rpm. You
> and I both know that the L series motor is
> capable of way above that, and if you are
> dragging the impeller along at say
> 50,000rpm, something could well break. The
> purpose of the turbo is to let the exhaust
> gases spin it up, the super spins it up at
> engine rpm's. The best bet would be to get a
> super unit geared for higher rpm's (geared
> down, I guess) intercool it, and run the
> bejeezus out of the boost. They make units
> upwards of 21lbs nowdays, plus the intake
> charge would be FAR cooler with an
> intercooled super than it would by an
> intercooled turbo - by default it would be
> anywhere from 70 to 110 degrees difference
> in ambient temperature, and that spells HP!!
> Timing can be advanced much farther without
> the risk of detonation, and, depending on
> carbureted or injected, a modified fuel
> curve could also benefit the motor by
> adjusting to the amount of boost being
> produced at a given rpm range. I have been
> mulling over the idea for a while, I have a
> blown/intercooled Mustang and it is a very
> efficient way to get HP without having to
> buy ANYTHING else for the car such as a
> timing management system etc.. Just another
> idea to throw into the fire!

> Tim

As far as overspinning, don't belt
driven supers have a certain amount of
slip built into the belt(non-cogged).
And also, aren't some supers offered
with pulley clutches which allow it
to be disengaged ?(is that correct
English)
Carlos L.
 
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